Very high intensity positron beam generated by LEP2 synchrotron radiation

This year (1996), the CERN large electron-positron collider (LEP) will produce electron positron collisions from accelerated beams with energies up to 80 GeV per beam, thus providing the highest energy, intense electron beam in the world. At LEP, a 4 T superconducting wiggler could be used to produce synchrotron radiation [1]. For an electron beam with an intensity of 9 mA, this unique γ-beam would contain photons in the energy range 1–100 MeV at an intensity up to 1016 γ/s mrad MeV. The laminar shape of the synchrotron beam can be used to build a converter that preserves some of the initial (at the production) forward collimation of the positron beam. The converter consists of 200 targets with individual thicknesses of 2 · 10−3X0, where X0 is the radiation length, spaced by 10 cm for a total length of 20 m. The 20 m target is contained in a solenoid to focus the positron beam. The e+ beam is transported by a solenoid and is energy dispersed by a pair of dipole magnets. The positron yield in the energy interval 1–2 MeV is Ne+ ∼ 1013 positron/s MeV at the production level. The flux of positrons that can be obtained at LEP2 is two orders of magnitude larger than that predicted for future projects [2].